There are numerous instances where it is desirable to provide a seal or sealing membrane on or adjacent one or more surfaces. Particularly in building constructions or industrial structures, it is often desirable to provide a seal or sealing membrane which has properties that can not only seal so as to prevent ingress of moisture and the like, but also accommodate movement of various construction materials that arise from normal expansion and contraction of these materials. Examples of such instances is on or adjacent expansion joints or similar assemblies and in the application of bitumen flashing. Throughout each day and the variety of seasons, building surfaces and other construction elements expand and contract due to normal warming and cooling. Where there is a meeting of surfaces, thermal stress induced by the thermal expansion and contraction can lead to cracking of the structures. This clearly compromises structural integrity of the total structure.
The problem can become compounded when the structure has a primary purpose of containing hazardous materials. As an example, bulk liquid storage tanks for petroleum generally experience high activity in filling and draining of the tank. This high loading and unloading activity can cause deflection of the base of the tank. Deflection of the base of the tank in turn can create a suction effect at the lip of the tank, permitting water and other substances to seep in underneath the tank. Over time, water seepage can lead to corrosion of the underside of the tank base, which not only brings about contamination of the surrounding ground and environment, but can also contaminate the remaining petroleum stored within the tank.
One known solution to circumvent problems such as these, or indeed of any instance where sealing is required but there are movement issues at or adjacent the respective sealing surfaces, is to provide a sealing membrane across the sealing surfaces. Referring again to the tank example, it has been known to install a “bootseal” comprised from a resilient epoxy compound having adhesive qualities as well as flexibility, across and over the tank lip and extending over the adjacent bitumen base surrounding the tank. The epoxy compound can be coupled with woven fibreglass for further reinforcement. The premise of the applied seal is that the intrinsic flexibility of the substance or substances from which the seal is manufactured, is sufficient to accommodate thermal expansion and contraction movements of the structure or structures to which it is applied.
However, it has been found that in at least some instances, an unfortunate effect in the application of a seal such as this is that the application of the seal itself can contribute to overstressing of one or more of the surfaces to which the seal is applied. Where construction of adjacent surfaces is not sufficiently strong, overstressing, typically from nothing more than normal thermal contraction and expansion, can lead to cracks in the surfaces. This cracking clearly compromises the structural purpose of the applied seal.
There is therefore a need for a product or assembly which can not only provide a seal or membrane between adjacent surfaces, but which can also accommodate movement issues at or adjacent the respective sealing surfaces without compromising the structural integrity of those surfaces.